1. Field of the Invention
The present invention relates to a method of manufacturing a honeycomb structure.
2. Discussion of the Background
A large number of techniques have been developed in relation to conversion of automobile exhaust gas. With an increase in traffic, however, countermeasures taken against exhaust gas have hardly been satisfactory. Not only in Japan but also globally, is automobile emission control going to be further tightened.
In order to meet such control of exhaust gas, catalyst supports capable of treating predetermined components contained in exhaust gas are used in exhaust gas converting systems. Further, a honeycomb structure is known as a member for such catalyst supports.
Common honeycomb structures have a honeycomb unit. This honeycomb unit has, for example, multiple cells (through holes) extending from one end face to another end face of the honeycomb unit along its longitudinal directions, and these cells are separated from each other by cell walls supporting a catalyst or cell walls formed of a catalyst. Accordingly, in the case of causing exhaust gas to flow through a honeycomb structure having such a honeycomb unit, substances contained in the exhaust gas, such as HC, CO, and/or NOx, are converted by the catalyst supported by the cell walls or the catalyst forming the cell walls, so that these components in the exhaust gas may be treated.
In particular, in systems called SCR (Selective Catalytic Reduction) systems, it is possible to decompose NOx in exhaust gas into nitrogen and water using ammonia. For example, WO 09/141,897 A1 discloses a honeycomb structure having a honeycomb unit containing zeolite usable in SCR systems. The entire contents of WO 09/141,897 A1 are incorporated herein by reference.
A honeycomb unit of the conventional honeycomb structure of WO 09/141,897 A1 is formed by manufacturing a honeycomb molded body by subjecting raw material paste containing inorganic particles, an inorganic binder, an organic binder, a molding aid, water, etc., to extrusion molding and thereafter firing this honeycomb molded body.